Recently, there has been known a technique in which the standard of IMS (IP Multimedia Subsystem) is equipped in an information processing device such as a cellular phone or the like, messages are communicated (transmitted/received) among mates (friends) and the information is registered in a server on a real-time basis so that the information is shared by the mates and the present states are mutually notified among the mates (see JP-A-2001-244928).
A presence information notifying function has been used as the function using IMS as described above. With respect to this presence information notifying function, it is expected that more intimate communications can be performed by mutually notifying, as presence information, communication means which users desire at present. With respect to cellular phones that mutually notify presence information to one another, it is desired that the presence information be mutually notified on a real-time basis not only in a case where the setting of some presence information is changed by a user, but also in a case where an application program is started, etc.
Particularly, in an information processing device such as a cellular phone or the like, three types of functions of telephone call, video telephone and PTT (Push To Talk) are mainly used as functions using a voice path (receiver, microphone). In the process of using one of these functions, the function of newly using another voice path cannot be started due to the fact that there is typically only one voice path.
In a case where resource competition of voice paths as described above occurs, it is desired to notify other cellular phones that “response impossible” is set as the present state and application programs using other voice paths are unusable when an application program requiring a voice path is started.